Chirped surface acoustic wave (SAW) correlator/expander

Abstract

A surface acoustic wave (SAW) expander based transmitter and correlator based receiver comprises SAW devices that perform expander or correlator functions based on the types of signals inputted to the SAW devices. The SAW devices incorporate chirp with adaptive interference and programmable coding capabilities. The SAW devices and method of operating the devices allow the implementation of very low power radios that overcome problems with temperature drift, lithography constraints and interference and jamming suffered by prior art implementations.

What is claimed is: 
     
       1. A surface acoustic wave (SAW) correlator-based receiver comprising:
 a splitter coupled to an antenna and to a first chirp correlator and a second chirp correlator, the splitter configured to split a signal received by the antenna into a first signal and a second signal;
 the first chirp correlator coupled to the splitter and configured to compress the first signal and the second chirp correlator coupled to the splitter and configured to compress the second signal, wherein the first and second chirp correlators are configured to be paired with a first and second chirp expander of a SAW expander-based transmitter, respectively; 
 a plurality of adaptive starting gate blocks coupled to the first and second chirp correlators and configured to mitigate interference in the first and second signals; and 
 a plurality of demodulation circuits coupled to the plurality of adaptive starting gate blocks and configured to demodulate the first and second signals to produce a detected output. 
 
 
     
     
       2. The SAW correlator-based receiver of  claim 1 , wherein the first and second chirp correlators comprise a SAW substrate with interdigital transducers (IDTs) configured to perform coding and chirp functions. 
     
     
       3. A chirped surface acoustic wave (SAW) communication system comprising:
 a SAW expander-based transmitter; and 
 a SAW correlator-based receiver, wherein the SAW expander-based transmitter and the SAW correlator-based receiver are located at the front end of a radio-frequency transmitter/receiver, 
 wherein the SAW expander-based transmitter comprises first and second interdigital transducers (IDTs) and the SAW correlator-based receiver comprises third and fourth IDTs, the first and third IDTs configured to implement programmable coding and the second and fourth IDTs configured to implement a chirp, and outputs of the second and fourth IDTs are configured to be symmetrically chirped in opposite directions and broken into sub-bands, the sub-bands available for summing or deletion for interference or jamming mitigation. 
 
     
     
       4. The chirped SAW communication system of  claim 3 , wherein inputs of the first and third IDTs are phase-coded to allow multiple access coding (CDMA). 
     
     
       5. The chirped SAW communication system of  claim 4 , wherein the first and third IDTs comprise slanted fingers. 
     
     
       6. The chirped SAW communication system of  claim 3 , wherein the SAW expander-based transmitter and the SAW correlator-based receiver are operated at a harmonic frequency. 
     
     
       7. The chirped SAW communication system of  claim 6 , wherein the harmonic frequency is the third harmonic frequency. 
     
     
       8. A method for chirped surface acoustic wave (SAW) communication comprising:
 generating a plurality of pulse trains from a plurality of switches on a plurality of chirp expanders in response to a data signal; 
 converting the plurality of pulse trains to generate at least one up ramping frequency pulse and at least one down ramping frequency pulse on a combiner; 
 combining the at least one up ramping frequency pulse and the at least one down ramping frequency pulse to generate a signal on a first antenna; 
 transmitting the signal from the first antenna; receiving the signal from a second antenna; 
 splitting the signal from the second antenna into at least a first sub-signal and a second sub-signal; 
 compressing the first and second sub-signals with a plurality of chirp correlators to generate a plurality of output signals; 
 pairing the chirp expanders and the chirp correlators, wherein the chirp expanders have a first time response and the chirp correlators have a second time response, the second time response being the inverse of the first time response; 
 demodulating the plurality of output signals with a plurality of demodulators; and generating commands from the demodulated output signals. 
 
     
     
       9. The method of  claim 8  further comprising increasing a bandwidth of chirp SAW communication circuit by slanting a plurality of fingers of a plurality of interdigital transducers (IDTs) of the chirp expanders and the chirp correlators. 
     
     
       10. The method of  claim 8 , wherein the chirp expanders and the chirp correlators are operations at a harmonic frequency. 
     
     
       11. A method to process signals at a surface acoustic wave (SAW) correlator-based receiver, the method comprising:
 splitting a signal received by an antenna into a first signal and a second signal; 
 
       pairing a first chirp correlator and second chirp correlator with a first chirp expander and second chirp expander of a SAW expander-based transmitter, respectively, wherein the first chirp correlator and the second chirp correlator are coupled to the antenna;
 compressing the first signal and the second signal using the first chirp correlator and the second chirp correlator, respectively; 
 mitigating interference in the first and second signals using a plurality of adaptive starting gate blocks coupled to the first and second chirp correlators; and 
 demodulating the first and second signals to produce a detected output.